This application relates to resistance welding guns. More particularly, the application relates to arm assemblies that support electrode arms.
Resistance welding guns are used in the automotive industry, for example, for spot welding a workpiece. Opposing arm assemblies are actuated to engage the workpiece with electrode arms provided on the arm assemblies. Numerous resistance welding guns are typically employed to spot weld a vehicle body, for example. However, the welding guns must be customized to reach the area to be spot welded, which results in many unique parts for the arm assemblies.
A modular design approach previously has been applied to resistance welding guns. This design approach focused on mass producing the welding gun body, which includes the actuator, transformer and arm assemblies (excluding the electrode arms). The electrode arms were unique to reach the area to be spot welded. The electrode arms are commonly made of high strength copper or aluminum alloys that are very expensive and may be difficult to fabricate into complex shapes. This is particularly problematic since the electrode arms are perishable due to the mechanical and thermal loads to which they are subjected during welding operations. As a result, while the cost of the welding gun bodies has dropped, the high cost of the electrode arms has offset the gains.
Furthermore, prior art modular resistance welding guns have been expensive in that they have utilized many high tolerance machined components to ensure alignment between opposing electrode ends. In the event of a misalignment of the electrode ends in the field, for example due to a crash, time consuming and costly repairs in the field must be employed to restore electrode alignment.
What is needed is improved modular resistance welding guns that reduce the overall cost of the gun assembly. Moreover, a modular welding gun is needed that provides improved alignment between the electrodes while reducing the high tolerance machining typically required of the gun components.